Field of the Invention
The present invention generally relates to a fiberglass reinforced mine roof and rib plate, and nut and bolt assembly, and, more particularly, to a fiberglass reinforced mine roof and rib plate, and nut and bolt assembly having a density greater than the density of the coal to which the plate and bolt are mounted or are to be mounted.
Description of Related Art
As is appreciated by those knowledgeable in the art, the use of electricity has been an essential part of the economy of the United States. More particularly, coal burning produces about 55% of the electricity generated in the U.S. In one use, the coal is in the form of powder and is known as “powdered coal” or “coal dust” because it is as fine as face powder in cosmetic makeup. The concept of burning coal that has been pulverized into fine powder stems from the belief that if coal is made fine enough, it will burn almost as easily and efficiently as a gas.
In general, the process of making powdered coal includes removing the coal from the earth, conveying the coal to equipment to crush the coal into smaller chunks, and conveying the chunks of coal to a washing station to wash the coal, and grinding the washed coal chunks into powered coal. In one washing station of particular interest in the present discussion, but not limiting thereto, the coal chunks are fed into a large liquid-filled tank. The coal floats to the surface while the impurities, e.g. but not limited thereto, sulfur and pieces of support safety devices used in the mine, float to the bottom. As is appreciated by those skilled in the art, the liquid has a density greater than the density of the coal and a density less than the densities of the impurities.
Although the process of cleaning the coal by washing is acceptable, there are limitations. More particularly, the coal is removed from the mines by grinding the coal from the roof and the sidewalls or ribs. During the grinding operation, any support safety devices mounted in or on the wall and roof of the mine are ground or shredded. The support safety devices are usually made of metal, e.g. but not limited to, steel, and the grinding of the safety devices generates metal pieces having sharp edges that cut into the conveyor belts of the conveyor equipment.
The support safety devices of interest in the present discussion, but not limited thereto, include the roof and rib (sidewall) plates, and nut and bolt assemblies holding the plates in position (“support systems”) that are used to provide surface control of mine roof and sidewalls. The surface control devices are made of metal to provide adequate stiffness characteristics that can help reduce or even eliminate progressive roof and rib failures. Mine roof and rib controls are typically managed by drilling a bore hole in a mine roof or sidewall, installing a first end of a mine roof bolt in the bore hole, positioning a channel, bearing plate, or mat adjacent to a second end of the mine roof bolt, mounting a nut on the second end of the bolt, securing the second end portion of the bolt in the roof or sidewall, and tightening the bolt to bias the channel plate, bearing plate, or mat against the rib or roof of the mine as the case may be. FIG. 16 herein shows a bearing plate of the invention biased against a roof of a mine.
Channel plates, bearing plates, roof channels, and mats help to further stabilize mine roof or rib strata, which may shift over time and can be a visual indicator that the mine roof bolts have been installed correctly. Of particular interest in the present discussion are rib plates used to stabilize the ribs and roof of coal mines until such time that the coal forming the ribs and roof is removed. More particularly, the coal forming the ribs and roof is removed using a rotating drum having an abrading surface. The drum is rotated and biased against the rib and roof to abrade the coal from the ribs and roof of the mine. The usual practice is to leave the rib and roof plates in position and abrade the coal, the plates, and the bolts.
One of the advantages of having the support safety devices made of metal is that metal has a density greater than the density of coal and sinks to the bottom of the liquid tank during the washing of the coal. One drawback of having the support safety devices made of metal is damage to the conveyors as discussed above. Another drawback is that during the abrading of the sidewall, metal particles are pressed into coal chunks and remain on the coal chunks as they pass through and exit the washing station. When the metal particles are ground with the coal chunks, the particles mix with the powdered coal and clog the powdered coal feed jets of the furnace causing a furnace shut down to clean the jets.
As can be appreciated, it would be advantageous to provide safety support devices that do not have the limitations of the presently available safety support devices discussed above.